This is possibly one of the most common biomechanical dysfunctions in the peripheral system. It is a frequent accompaniment to an inversion injury. Following inversion injury, the talus may become anteriorly fixed. This should mean that it couldn’t glide posteriorly at all, therefore completely limiting dorsiflexion of the ankle. However, only a few degrees of dorsiflexion are actually lost. The subluxation therefore cannot be anterior. Rather the talus is subluxed into medial rotation. This would completely limit lateral rotation, which is the conjunct rotation of dorsiflexion. As only the final part of dorsiflexion relies on conjunct rotation, only a few degrees of range are lost. Rarely, a posterior subluxation will be encountered, the traction manipulation is appropriate for this condition but the J-stroke manipulation, because it is directional and posterior is not.
Anatomy and Biomechanics
The ankle is a modified sellar synovial joint with one degree of freedom, plantaflexion and dorsiflexion. The talus presents a convex surface to the cruris for the degree of freedom therefore its arthrokinematic is opposite its osteokinematic. For dorsiflexion it glides posteriorly and for plantaflexion anteriorly, Its stability is dependent on its collateral ligaments and the integrity of the inferior tibiofibular joint, which in turn relies on anterior, posterior and interosseus ligaments. During the last few degrees of dorsiflexion, the talus rotates laterally as a conjunct movement.
The passive physiological motion of dorsiflexion is limited by 5-10 degrees by an abrupt hard (but not bony) end feel. The same end feel limits the posterior talar glide. Plantaflexion and anterior glide are normal with either a normal capsular or a soft capsular end feel (if the anterior capsule has been over-stretched). If the talar swing test has been utilized in addition to the above, the tester will feel the loss of the lateral rotation of the talus with dorsiflexion.
The common treatment for this condition is done in error. The mistake is in believing that the plantaflexors which are tight. This idea can easily be dispelled. First, it cannot be the gastrocnemius as the constant length phenomenon is absent when the knee is flexed. So it could be the soleus, but this would not limit the arthrokinematic (joint glide) nor alter its end feel, both of which are noted on examination. In fact stretching the plantaflexors is exactly the wrong treatment. It will eventually restore the range of dorsiflexion but it usually does so by spreading the mortise formed between the tibia and fibula. Instead of this, a simple manipulation usually effects a cure. The technique that will be described is the traction manipulation. This is non-directional as far as the lesion is concerned.
The problem joint is distracted and then let go to reposition normally (with any luck). The patient lies supine with the unaffected leg’s knee flexed to protect the back (if back pain is present, the patient can pull the knee up to the chest). The PT stands in line with the leg by the foot. The PT’s hands are wrapped around the instep of the foot so that the little or ring finger of one hand is over the neck of talus. The thumbs lay along the sole of the foot and in this position, the thumbs maintain the posture of the foot, preventing it from dorsiflexion when the thrust is applied. The foot is positioned in its resting (neutral) position to permit maximum room within the joint. The PT pulling the hands towards the body takes up partial distraction slack. The manipulation is effected by a sharp pull distally in line with the tibia, causing the talus to distract from the mortise.
The J-stoke manipulation is reserved for the subluxation resistant to the simple traction technique. This is a combination of distraction and posterior thrust causing a scooping movement to occur (the J). Much care must be taken to ensure that dorsiflexion does not occur during the manipulation.
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